In a typical IPM motor, a plurality of through holes each extending in an axial direction are defined in an outer circumferential portion of a rotor core, and magnets are embedded in these through holes. The magnets are fixed to the rotor core through an adhesive.
A method of using the adhesive for fixing the magnets to the rotor core necessitates a series of processes including a process of application of the adhesive, a process of heating and thereby curing the adhesive, and a process of checking adhesion. This series of processes involves heavy burdens in terms of equipment and labor, and takes a lot of time to be completed. Moreover, this method is also unfavorable in terms of quality and costs.
In view of this, techniques described in JP-A 2008-193809, JP-A 2001-37123, and JP-A 11-332146 do not use the adhesive, but join and fix end plates to both ends of a rotor core through a plurality of rivets or the like.
JP-A 9-74699 discloses a rotor that is designed to achieve an improvement in ease of assembling, although this rotor is not a rotor of an IPM motor. This rotor includes a cylindrical magnet, a disc portion, and an inertia ring. Each of the disc portion and the inertia ring is attached to an opposite end portion of the magnet. Three engagement arms, each of which is arranged to extend in the axial direction, are arranged on an outer circumference of the disc portion. Each engagement arm includes a locking claw defined in an end thereof. The inertia ring includes recessed portions defined therein, and the locking claw of each engagement arm is brought into engagement with a separate one of the recessed portions to fit the inertia ring and so on to the magnet.